I managed a project to replace a failing UPS and it included UPS support for the air con.

There were two comms rooms each full of servers etc. having air con rated at 40kW max. Both rooms full to capacity. There was also a large office floor to support on UPS. Total load 160kW.

So 3 x 80kW UPS (giving N+1) were installed for the comms rooms and the office floor.

Then it was decided that the comms room air con must run when the servers, etc are on UPS, so a 4th 80kW UPS was installed. Thus the load of the 4th UPS was (1) 2 x 40kW air con and (2) one small air con unit in the UPS room (which housed 4 * 80kW UPS).

I do not recall how much overkill there was with the 4th 80kW UPS - it could be another 80kW UPS was purchased to match the first 3 and give future flexibility.